M. S. Pappalardo

Calix[4]arene Decorated with Four Tn Antigen Glycomimetic Units and P3CS Immunoadjuvant : Synthesis, Characterization, and Anticancer Immunological Evaluation

A novel anticancer vaccine candidate built on a nonpeptidic scaffold has been synthesized. Four S-Tn tumor-associated glycomimetic antigens have been clustered onto a calix[4]arene scaffold bearing an immunoadjuvant moiety (P3CS). The immunogenicity of the synthetic construct has been investigated by immunization of mice in vivo. ELISA assay has evidenced that the tetravalent construct stimulates a higher production of anti-Tn antigen IgG antibodies when compared to an analogous monovalent compound. This result is ascribable to an antigen cluster effect and makes the reported vaccine candidate a good mimic of the natural motifs present on the mucine surface.

Synthesis and Immunostimulating Activity of A Thioglycolipopeptide Glycomimetic As A Potential Anticancer Vaccine Derived From Tn Antigen

ABSTRACT The Tn epitope is one of the tumor associated O-linked cell surface glycopeptides. It is expressed in over 70% of human epithelial cancers such as lung, colon, stomach and breast carcinomas. The glycosidic linkage of the Tn antigen, between N-acetylgalactosamine and serine or threonine, can be cleaved either chemically or enzymatically in the presence of glycosidases. The latter case is particularly a problem in vivo. Therefore, it would be of great interest to obtain a metabolically stable analogue of the Tn antigen that maintains or improves the immunogenic activity of the latter. The purpose of this work was to synthesize a totally synthetic vaccine using a chemically and metabolically stable glycomimetic of the Tn antigen in which the interglycosidic oxygen was replaced by a sulphur atom (S-Tn). The S-Tn thioglycopeptide was linked to the P3CS immunoadjuvant to obtain the potential S-Tn vaccine. Moreover, we synthesized the natural Tn antigen and derivatized it similarly to obtain the Tn vaccine. Last, we evaluated the immunostimulating activity of the two synthetic potential vaccines in vitro using cultured mouse splenocytes. The S-Tn construct showed immunostimulating activity comparable, in terms of maximal response, to the Tn analogue. Moreover, due to its higher stability the S-Tn construct reached its maximal effect at lower doses compared to the Tn analogue.

First Self-Adjuvant Multicomponent Potential Vaccine Candidates by Tethering of Four or Eight MUC1 Antigenic Immunodominant PDTRP Units on a Calixarene Platform: Synthesis and Biological Evaluation

MUC1 protein overexpressed in human epithelial carcinoma is a target in development of novel anticancer vaccines. Multiple units of immunodominant B-cell epitope PDTRP MUC1 core sequence were conjugated to calix[4,8]arene platforms containing TLR2 ligand, to produce two novel anticancer self-adjuvant vaccine candidates. The immunogenicity of the synthetic constructs was investigated by immunization of mice in vivo. ELISA assay evidenced that the vaccine candidates stimulate anti MUC1 IgG antibody production (major for the octavalent construct) and no additive effect but a multivalency effect was observed when compared to an analogous monovalent. Octa- and tetravalent constructs lacking in PDTRP peptide moieties did not show anti MUC1 IgG antibody production in mice. The antibodies induced by the synthesized constructs are able to recognize the MUC1 structures present on MCF7 tumor cells. The results display that calixarenes are convenient platforms for building multicomponent self-adjuvant vaccine constructs promising as immunotherapeutic anticancer agents.

Synthesis of (+)- and (−)-cis-2-[(1-adamantylamino)-methyl]-1-phenylcyclopropane derivatives as high affinity probes for σ1 and σ2 binding sites

Selective ligands for either sigma1 (σ1) or σ2 binding sites are potentially useful for gaining a better understanding of the physiological functions of these proteins. Moreover, potent and selective homochiral σ1 and σ2 binding site ligands represent leads to potential radioligands for tumour imaging with positron emission tomography (PET). On the basis of their structural similarity to previous leads, new (+)- and (−)-cis-2-[(1-adamantylamino)-methyl]-1-phenylcyclopropane derivatives were synthesised and their binding affinities for σ1 and σ2 binding sites were determined. Each enantiomer showed high affinity for both σ1 and σ2 binding sites, but only (−)-cis-methyl-2-{[1-adamantyl(methyl)amino]methyl}-1-phenylcyclopropane-carboxylate, (−)-4, showed appreciable selectivity for binding to σ1 versus σ2 sites. The enantiomers of cis-(2-{[1-adamantyl(methyl)amino]methyl}-1-phenylcyclopropyl)methanol, 6, expressed the highest affinity for σ1 and σ2 binding sites. Ligands (−)-4, (+)-6 and (−)-6 might be rapidly labelled in their N-methyl groups by methylation of the N-desmethyl analogues with [11C]iodomethane to provide prospective radioligands for PET. The N-desmethyl analogues, which are also high affinity ligands, were prepared and shown to undergo satisfactory methylation with iodomethane.

Specific κ opioid receptor agonists

Abstract The results of studies on the design of a heterocyclic scaffold for the dynorphin A pharmacophore and on structure–affinity relationships in the MPCB/CCB series are described. The representative ligands provide insights to binding modes of benzomorphan derivatives to the κ opioid receptor.

Bivalent opioid peptides synthesized from μ selective monomers display preferential selectivity for δ receptors

Abstract A series of dimeric opioid peptides derived from μ selective compounds was synthesized to investigate whether μ and δ receptors coexist as distinct recognition sites on the same receptor complex. Some compounds were several times more potent than the corresponding monomers in the MVD (mouse vas deferens) smooth muscle preparation, which is rich in δ receptors, but yet retaining substantial activity in the GPI (guinea pig ileum). It is suggested that δ receptors might differ from μ receptors in that they possess an additional accessory recognition site, to which could bind a particular amino acid residue present in the second halves of these bivalent ligands. This residue could play the role of “address” at δ opioid receptors.

Synthesis of new P3CS derivatives and their mitogenic activity on in vitro mice splenocytes.

Vaccination against tumors represents a relevant issue in current human cancer therapy. The N-terminal part of the lipoprotein from the outer membrane of Escherichia coli, tripalmitoyl-S-glyceryl-Cys-Ser (P(3)CS) and analogs with longer aminoacidic sequence are polyclonal activators for B-lymphocytes. Previous study reported that their N-2,2,2-trichloroethoxycarbonyl (Troc) derivatives increase immunocyte mitogenic activity. Therefore, in order to obtain compounds of greater activity and to investigate relationships between molecular structure of S-glyceryl skeleton and biological activity, we synthesized new Troc derivatives of P(3)CS. The mitogenicity of compounds was determined in vitro, by measuring in vitro [3H]-thymidine incorporation into splenocytes from Balb/c mice. Concentrations of compounds ranged from 0 to 64 micro g/ml. In particular, S-[2,3-bis(trichloroethoxycarbonyloxy)]-N-trichloroethoxycarbonyl dipeptide derivative exhibited significant mitogenic activity endowed with high pharmacological potency. These new series of compounds could be used as potent immunoadjuvants for the development of novel synthetic vaccines for tumor immunotherapy.